I've been working with following combo: No way going back to Notepad++

- platformio to generate IDE project for QtCreator. http://docs.platformio.org/en/stable/ide/qtcreator.html
- QtCreator as IDE. Quite fast with autocomplete and finds quickly declarations/methods and you can compile your project much much faster (platformio) than Arduino IDE to check for errors. http://www.stm32duino.com/viewtopic.php?t=1375
- for uploading I have to use Arduino IDE for now
- next thing is to try debugging with launching BMP GDB from QtCreator. QtCreator has nice debugging interface.